Supervisory signal for telephone-switchboards.



N0. 638,426. Patented Dec. 5, i899. C. E. SCRIBNER. SUPERVISORY SIGNALFOR TELEPHONE SWITGHBOARDS.

(Application filed Feb. 14, 1898.)

Mam-m- Witnesses: Inventor:

/ by M h i S Atheys THE NORRIS PETERS DO.A PHOTO-LITNO., WASHINGTON, DC.

NlTE STATES PATENT EEIciE,

CHARLES E. soRIBNEE, or CHICAGO, ILLINOIS, ASSIGNOR TO THE WEsTEEnELEoTEIo COMPANY, OF SAME PLACE.

UPERVlSORY SIGNAL FOR T ELEPHONE-SWITCHBOARDS.

SPECIFICATION forming part of Letters Patent No. 638,426, dated December5, 1899. Application filed February 14, 1898. Serial No. 670,272. (Nomodel.)

To all whom it may concern: operator and serves merely to distract herat- Be it known that I, CHARLES E. ScEIBNEE, tention. a citizen of theUnited States, residing at Ohi- My invention applies to signalingsystems it cago, in the county of Cook and State of Illiof this generaltype and. aims to permit the 55 5 nois, have invented a certain new anduseful display of asupervisory signal associated with Improvement inSupervisory Signals forTelethe called line until the called partyresponds phone-Switchboards, (Case No. 456,) of which and thereafter toagain permit its display only the following is a full, clear, concise,and eX- to indicate a call for disconnection in accordact description.ance with the replacement of both telephones 6o This invention concernssupervisory sigon their switches at the substations.

nals for association with united telephone- To this end it consists inthe combination, lines to indicate to the attendant the condiwith unitedlines or with link conductors for b tion of the telephonic appliances atthe subtemporarily uniting lines,ofasupervisory sigstations of thelines, the object of the invennaldesigned to come into a bridge of theline, 65 I tion being to provide a means of controlling together with asource of current, an electrothe supervisory signal in such a way thatit magnet having a winding in each line, and may act in response to onlythose acts of the switch contacts controlled by the magnet subscriberswhich are of interest to the operadapted to connect the supervisorysignal ator in the performance of her duties. with the line of thecalled party when inert 70 I In establishing and supervising a connecandto connect it with both lines when ex- I tion between telephone-lines anoperator, afcited, whereby the supervisory signal inditer makingconnection with the calling-line cates a current in the line of thecalled party t and receiving the order for the required conwhen thetelephone at the called station is renection, requires informationthereafter only moved from its switch for use, but thereafter 75 2 5 ofthe response of the called party to the call is controlled by current inboth lines and and, finally, of the replacement of the teleserves toindicate only the cessation of ourphones on their supports at bothstations When rent in both. i1 conversation is finished. The inventionfurther consists in means for t It has been common intelephone-switchmaintaining the hidden condition of the sig- 8o 0 boardsof modern type to provide in connecnal while the plugs or linkconductors are tion with united telephone-lines a source of not in use.current, a switch at each substation for con- The invention is describedin connection trolling current in the line, and one or more with theattached drawing. The figure repsupervisory signals associated with bothor resents two telephone-lines terminating in 85 3 5 with each of thelines and responsive to such the usual calling and connecting appliancesicurrents. In following some modes of superin a telephone-switchboardand a pair of vising a single supervisory signal has been plugs withtheir link conductors or plug-cirprovided in a bridge of theplug-circuit or cuit for uniting the lines, the latter applilinkconnector uniting the lines. This plan ances being provided with asupervisory sigo 40 has been unsatisfactory in that it imparted nal inaccordance with the invention. The to the operator no information as tothe restations of the telephone-lines are equipped spouse of the calledparty. In other switchwith the usual signal-bell, telephone, and

boards a supervisory signal has been provided switch, the circuits beingadapted for the proin connection with each line, each signal reductionofa closed circuit through the tele- 5 spending only to current in itsown line; but phones when the receiver is taken for use.

this plan is inefficient in that it requires the The line conductors 1and 2 from the staoperator to observe two signals in order to astionapparatus are led to a spring-jack a in certain the call fordisconnection and that it the telephone-switchboard and. bynormallypermits either of the two signals to be dis closed extensionstherefrom through an indi- ICO 5o played at intervals during theconnection, vidual or line signal I) to a source of current when itsindication is of no assistance to the o. The line-signal b will then bedisplayed the plugs are united by a continuous conto the operator toindicate a call when the telephone at the substation of thecorresponding line is removed from its switch through the agency ofcurrent flowing from the source 0 through the closed circuit at thesubstation. The switchboard is furnished with a number of pairs of plugsd d with their associated appliances. One paironlyis here shown. Theseplugs form the terminals of a plug-circuit which while the lines are inuse forms acoutinuous conducting-circuit between the lines. With theplug-circuit are associated the usual calling-key e for connecting agenerator of signaling-current with the plug 61, which is designed foruse in connecting to lines called for, and with a listening-keyfforbringing the operators telephone into connection with the plug-circuit.

' In accordance with this invention a supervisory signal 9 is associatedwith each pair of plugs or plug-circuit. The circuit connections of thissignal with the plug-circuit are controlled by a relay It, provided withan armature-lever it, playing between two contact-anvils h and h Thisrelay has two windings b and 71 The former of these windings isconnected in a conductor 3, leading from the front contact 712 of therelay to the sleeve of the answering-plugd,while the latter winding itis connected in a conductor 4., leading from the switch-lever h to thesleeve-contact of calling-plug d. The tip-contact pieces of ductor 5.The supervisory signal 9 is provided with two windings, which areincluded serially in a conductor 6,which forms a bridge of theplug-circuit, uniting conductors 4 and 5 thereof. A source of current iis interposed in the bridge-conductor between the windings of the signalg. These windings should of course be of high impedance in order thatthe shunting of telephonic current through the bridge may be prevented.One of the plugs, preferably the answering-plug d, rests in aseatprovided with a plug-seat switch 7c, which is designed to close acircuit while the plug is in its seat. This switch controls thecontinuity of a conductor 7, terminating at one extremity in thecontact-point 7L3 of relay h and connecting at its other extremity withthat pole of battery 2' which is connected with conductor 6 of theplug-circuit or otherwise in any suitable way to bring the battery intoa local circuit, including one or both windings of the supervisorysignal, when the contacts h h are closed, the connection being shown asextending to earth. While the apparatus of the switchboard is idle themagnet 71 is inert and a local circuit is formed from battery t throughone winding 9' of the supervisory signal, through wire 6, through thecontacts h h and through wire '7, the contacts of plug-seat switch beingclosed. The magnet of signal 9 is thus excited, and the indicator of thesignal which is designed to appear when the magnet is inert is hidden.An operator on observing a call-signal displayed 1 in one of theline-indicators follows the usual steps of inserting answering-plug dinto the spring-jack of the calling-line, obtaining the subscribersorder for connection with another line, inserting calling-plug cl in aspring-jack of the line called for, and operating the ringing-key e toring the bell at the station thereof. Inasmuch as these operations arefamiliar to those skilled in the art of telephony, I do not pause totrace them in detail. When the plug d is raised from its seat, theplug-seat switch 7c breaks the conductor 7 interrupting the current inthe local circuit, and the indicator of supervisory signal g comes intoview. When the plug 61' is connected with the line called for, thecircuit through signal g remains broken, being openat thetelephoneswitch at the substation until the called party, responding tothe call, takes the telephone for use. Then the telephone-switch at thesubstation closes circuit between line conductors 1 and 2, therebycompleting a circuit through the supervisory signal and the relay h,which may be traced as follows: from battery 'i through a portion ofconductor 6, including a winding of the supervisory signal, thencethrough conductor 4 of the plugcircuit, including the winding h" ofrelay h, to line conductor 2, returning by line conductor 1, and findingcircuit to battery t' through a portion of conductor 5 and wire 6,including the other winding of supervisory signal g. This signal thusbecomes excited and its indicator is concealed. This signifies to theoperator that the party called for has responded to the call. At thesame time magnet It becomes actuated, being excited by current flowingin the winding h, and brings its armature-lever h into contact with theanvil 71 This movement of the armature thus unites conductors 3 and 4,forming a continuous conductor between the sleeves of the plugs andbetween the two line conduetorsl of the lines to be united. Thereaftercurrent flows from the bridge 6 to both the called and the callinglines. remain excited as long as the telephone at either station is inuse. The current traversing the windingsof the supervisory signal 9 isalso rendered independent of the condition of the apparatus at eitherstation alone,so that the magnet will remain excited and the signal willremain hidden as long as either telephone is off its switch. When at thetermination of conversation the users of the telephones at both stationsreplace their receiving instruments on the telephone switches, currentthrough the windings of the supervisory signal g and of the relaymagneth is interrupted and the magnets of both become inert. The supervisorysignal then displays its indicator, and this second display of theindicator shows the operator that the use of the line is finished. Shetherefore removes the plugs (Z and d from the spring-jacks into whichthey are inserted and places them in their resting-seats. Thereplacement of plug IIO The magnet will therefore d in its seat causesthe switch 70 to close the break in wire 7, and, inasmuch as thearmature has come to rest on its contact it, completes the circuitthrough the supervisory signal and efiects the concealment of its indicator. Thus the indicators of all signals associated with plugs whichare not in use are hidden. The display of an indicator immediately afterthe establishment of connection with a line indicates that no responsehas been made to the call sent. The signal is hidden when the calledparty takes the telephone for use, and the signal is thereafterdisplayed only when at the termination of the use of the line bothtelephones are returned to their supports. This invention thus avoidsall confusion of signals and eliminates all indications on the part ofthe signals, excepting those which are found in practice to be essentialto the proper establishment and supervision of the connection.

The invention 'is defined in the following claims:

1. The combination with united telephonelines each provided at itsstation with means for determining the flow of current in the line inthe use of the telephone, a bridge of the united lines and a supervisorysignal and a source of current included therein, of a relay with twowindings, one included in the line to each station between said stationand the bridge, the switch-contacts of the said relay being adapted tobreak the circuit of the lines between the bridge and thecalling-station when the magnet is inert; whereby the supervisory signalis rendered responsive to current in both telephone-lines, substantiallyas and for the purpose set forth.

2. The combination with telephone-lines each provided with means at itsstation for determining the flow of current in the line in the use ofthe telephone, and link conductors uniting the lines, of a bridgebetween said link conductors, and a supervisory signal and a source ofcurrent included therein, a calling-key in said link conductors adaptedto connect a source of calling-current with one of said lines, a relayhaving two windings one being placed in a link conductor toward eachstation, between the station and said bridge, the switch-contacts ofsaid relay being open when the relay is inert, said switch-contactsbeing interposed in the link conductor between the said bridge and thecalling-station, as described.

3. The combination with two telephonelines each provided at its stationwith a switch for determining the flow of currentin the line during theuse of the telephone, of a bridge of the circuit, a supervisory'signaland a source of current in the bridge, a magnetwinding in a lineconductor to each station between said station and the bridge, a normalbreak of the line-circuit between the bridge and the calling-station,and switch-contacts actuated by said magnet-windings adapted to closethe break when the winding in circuit with the called station isexcited, as described.

4:. In combination,a telephone-line provided at its station with meansfor determining the flow of current in the line during the use of thetelephone, a pair of plugs and the plugcircuit thereof for makingconnection with the line, a bridge of the plug-circuit, a supervisorysignal and a source of current in the bridge, a magnet with twowindings, one of said windings beingin the conductor leading from saidbridge to each station, switch-con tacts controlled by the saidwindings,one pair of said contacts adapted to be closed when the magnetis excited being interposed in a conductor of the plug-circuit betweensaid bridge and one of the stations, and other switch-con tacts adaptedto be closed when the magnet is inert controlling a local circuitincluding a winding of the supervisory signal together with a source ofcurrent, as described.

5.- In combination with telephone lines, each provided with a switch atits station for determining the flow of current in the line during theuse of the telephone, a pair of plugs and the plug-circuit thereof formaking connection between lines,a bridge of the plugcircuit, and asupervisory signal and source of current therein, a relay-magnet withtwo 5 windings,one of said windings being included in the plug-circuitat each side of the bridge, switch-contacts of the relay adapted to beclosed when the relay is excited interposed in the conductor of theplug-circuit with one of said magnet-windings, other switch-contacts ofthe relay adapted to be closed when the magnet is inert, a local circuitof the supervisory signal including a source of current controlled bysaid last-mentioned switch-contacts of the relay, and a plug-seat switchfor one of the plugs adapted to open the said 10- cal circuit when theplug is removed from its socket, substantially as described.

In witness whereof I hereunto subscribe my name this 31st day ofJanuary, A. D. 1898.

CHARLES E. SORIBNER.

Witnesses ELLA EDLER, PEARLE CLENDENING.

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